1. Field of the Invention
The present invention relates to a package and socket unit and more particularly, to a package and socket unit housing a pin grid array package, used in a burn-in process whereby an initial test for an IC device, for example, a high temperature test, is carried out, and a carrier in used to hold the package.
2. Description of the Related Art
A PGA (Pin Grid Array) package in which a plurality of pins are perpendicularly projected in arrays is well known as an element of IC devices used, for example, in a supercomputor. Currently, the degree of density of the IC device has gradually increased and the PGA package has been correspondingly gradually miniaturized; for example, a PGA package having about 260 pins set in an area 30 mm has been produced wherein the pins have a very small diameter of, e.g., 0.4 mm.
When the production of a PGA package is completed, a burn-in process used for a high temperature test is usually carried out at an early stage of the testing of the IC device. In this high temperature test, the PGA package is usually kept at a temperature of about 120.degree. C. for a prolonged time, e.g., 48 to 96 hours, to determine whether failures such as wire-breaks have occurred.
To carry out the high temperature test, an electric current must be supplied to the IC device to be tested, and thus a socket connectable to power source pins (leads) among the pins of the PGA package, is provided and the power source pins are plugged into the socket to enable an electric current to be supplied through contacts in the socket which receive the power source pins.
When, however, the number of pins of the PGA package is very high, and accordingly the pitch between the pins is greatly reduced, failures occur due to an incorrect mating between the pin and the contacts of the socket. To ensure a satisfactory contact between the power source pins and the contacts of the socket, the contacts must be precisely positioned, and therefore, the socket production costs are very high.
Further, when the number of pins is increased, the pin diameter necessarily becomes smaller as described above, and therefore, when the power source pins are mated with contacts of a socket before carrying out the burn-in process, the power source pins are often bent and sometimes broken, which reduces the productivity yield. This problem also occurs with the pins for signal lines.
Japanese unexamined patent publication (Kokai) No. 57-117252 published on July 6, 1984 discloses a dummy test pad having bonding pads connected thereto. The dummy pad is arranged outside the bonding pads and is used to test and detect failures of the pads. Accordingly, if the technique of using this dummy pad is utilized for the above-described burn-in process, the above problems such as bending or breaking of the power source pins etc., can be solved.